*{
    margin: 0;
    padding: 0;
}
.box{
    width: 400px;
    height: 50px;
    border: 1px solid red;
    display: flex;
    justify-content: space-between;
    align-items: center;
    .item{
        flex-grow: 1;
        text-align: center;
    }
}